300 tdi ABS Anyone had this fault ?

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.

remedave

New Member
Posts
283
I am in the process of sorting the ABS out fairly simple, i have changed the ECU and 2 sensors and closed all air gaps and done all wheel bearings, the Abs light blinks when the ignition is turned on to say no faults (after i had cleared them) but the light refuses to extinguish until you reach a road speed of around 50 mph then it stays of and is fine apart from when you apply the brake below say 10MPH and the abs kicks in for no reason, this doesn't put the light on. then the next time you start the disco the light blinks no codes again then your ding the same all over again over 50 mph etc etc, i have done 200 miles or so like this and no change, the MOT is due and i am pulling my hair out :violent:
 
were the two sensors new and the same manufacturer? ...cos i presume the ECU is used anyway...and then nothing is easy to rule out ... this fault looks very like ECU fault to me... or if the sensors are different they could missbehave like that cos they have different resistance from the beginning albeit it is within the accepted range( between 950 and 1100 0hm)
 
I have checked the resistance it is within range, the sensor that was replaced was a one removed from a scrapper and the Ecu was too, the previous Ecu failed at the first test self diagnosing as bollixed, this Ecu was fine the the scrapper all the components come of, trying to sort the ABS out i have only ever had air gap faults (due to the wheel bearings and swivels been really lose) but these have since gone, its as if its not getting a input for speed ?? as if its 50MPH out ????

ABS light still on after pulling away, the ABS still cuts in at slow speeds, you can then go to 55mph the light goes off, stamp on the brakes and it locks up !!! the pull up at at around 10mph the ABS goes mental,

And still no fault codes its doing my head in nothing to go on if it would just throw a code up i have ragged it down 3 miles of farm track still nothing

were does it get its speed signal from to knock the ABS light of i truly think thats the cause as this disco has had so much butchering done by absolute incompetent tits its unreal
 
you can't diagnose properly a system which is built from scrap cos you dont know which component is 100% good or not... what I said is that even though the sensor's resistance is within range it's important to be as close as possible otherwise based on different inputs at the same speed(if e'g one sensor is 970 and the other 1070 ohm) the system gets completely mixed up ... I had something similar long time ago and only after I put 4 new wabco sensors the symptom went away... I ruled out the ECU by swapping it from a friend's well working car... you should make surecthat the ECU is 100% perfect though

unplug each sensor, suspend the car, start it, let the wheels spin constantly and measure AC volts on the outputs if you find more than 3% difference you need NEW same make sensors...cos there's a difference even between new ones from different manufacturers....
 
I hear what your saying, UGGHHH, i think you could be onto summit as the O/S/F sensor was replaced due to open circuit, it was a break in the wire that i found and just nipped it together and drove 20 yards the light extinguished then, and since then the only only thing i have done is replaced that sensor.

But the question still remains this bloody system is loopy its not wired right so to speak !!! if i knew how the system measured speed then i think i would be able to crack it.

I thought it might take a input from the speedo head or transfer box ? or maybe it takes a reading from 1 ABS sensor ? it can be all of them otherwise the light would go out as it should and it would throw a fault code along the lines of air gap or something.

Its got to be something silly, as far as i can tell the ECU thinks the car is travelling very slow hence the light not extinguishing as it should and the Abs not reacting correctly
 
Just looking throughout the last 2 sets of fault codes

5-12 Sensor or wiring on right hand front wheel speed sensor.
2-12 Air gap F/R
2-13 AIRGAP L/R

these were reset without any work then these come up after 100 miles or so

5-12 Sensor or wiring on right hand front wheel speed sensor.
2-15 AIRGAP R/R
2-13 AIRGAP L/R

the above has now be actioned well i say actioned the gaps have been tapped in etc. and as i say above many miles driven with out any fault codes but comedy brakes.

The one that does make me think it could be the fault is 5-12 Sensor or wiring on right hand front wheel speed sensor, this has cropped up twice now and i have not done anything except hammer it home but what exactly does it mean ?? i might swap it for the passenger side see if i can get it to throw a fault code if it does and its L/H wheel sensor then i have cracked it.

The whole thing is just strange if it is that sensor then that would mean the road speed for the ECU is calculated from 1 wheel to knock of the ABS light ?:confused:
 
the speed is calculated from all the sensors but so are all the inputs compared and for the system to work well at a calculated speed the inputs from the sensors must be very close to each other otherwise the system 'assumes' there's a wheel slipping and acts accordingly = ABS kicks in while braking even without reason or at the target speed it's mixed up by different inputs without logging a fault as the sensors and air gaps are within accepted range but the inputs are too different to extinguish the warning... IMO if you want to make it work well bite the bullet and use new sensors and 100% confirmed good ECU... you can't build a well working system out of scrap
 
have you changed any tyres recently? Reason I ask is that after a tyre went flat I put the spare on mine and altho the same size it was a different brand and made the abs very unstable and kick in all the time, it did not cause your fault of the abs light going out until reaching 50 tho.
 
Cheers for the replies i am going to put the money on the sensor i changed, but i am as tight as a tight thing, i will keep driving until i get a code to work of sooner or later it will put up a code and i will act on that. its such a basic system grrrrrr
 
well today was the day after driving like a complete tit around a field jumping and dough nutting it, its final thrown up a error code twice yay

5-12 front right sensor wiring

will change that then see were we are from there
 
Right after digging and digging i am at this point.

After using my car data docs attached here for anyones reference i have come to the conclusion the front R/H wheel sensor is U/S

Values
resistance pass
AC Volts fail - does not generate 0,4 v until 30MPH

View attachment ABS_D1 diagnose.pdf

I will change the sensor lets not for get this system is the same used on the P38 so pass on the info.
 
Right sensor changed same fault

5-12 o/s/f sensor wiring fault

its not he ECU

I have taken the values from the multi plug connector at the ECU and the 2 pin connector that connects the ABS sensor to the Harness in the engine bay the values are exactly the same.

What the hell is going on ??? the new sensor was that new surly 2 sensors can't be the same faulty?? they both test OK on the resistance so in theory should work.

Could it be the ABS ring in the Swivel ? but i would have thought that would throw a Air gap to much code ?

Any help please ? i really don't want to strip the swivel.

MOT over due so looks like its a ABS to OIL pressure gig.
 
Just can't find any reference to this problem i would seem rare than rare if i remember right the exited ring is fitted to / part of the internal cv right so for this to have failed it would throw a air gap fault.

With the Fluke attached it is producing a AC volt .4 is achieved at 30 mph this is too low it should be achieved at around 5 MPH all the other sensors achieve .4v at 5 MPH, however the ABS light will not extinguish until the vehicle reaches 56MPH then after driving round for a few miles and stamping on the brakes on a lose surface it will put the ABS light on fault code 5-12 every time

Its seriously doing my head in.
 
OK,
vehicle suspended in drive at tick over all sensors produce around 1V AC except the OSF its half that at 0.5 v why ????????????

i have removed the sensor looked inside the hub its fine no teeth missing wheel bearings are good the only thing that i have ever done to that side is remove shims as there was excess play in the swivel
the brand new sensor it touching the exciter ring as it has marked the end of it i truly give up what more can i do ?
 
my left hand front sensor gives me similar but not same problems, mine the light either stays on or comes on after quite driving an hour or more, or sometimes afer hitting a big bump like railway crossing, Usually problem from blink codes is air gap but also sometimes wiring. I can usually push the sensor in a couple of mm, I ve no idea why it moves out it has new wheel bearings, and pushing it in seems to make the abs work better but not for long.

Once I changed a wheel and the problem got 10x worse. With the light on pretty much all the time and abs kicking in as well.

I have wondered if the oil level or type can make a difference to the sensor as I have a bad leak from that side even with a new oil seal so it has fresh 80/90 oil in it unlike the other side, a long shot I know but it might have something to do with it!

Ive also wondered if some of the toothed rings are not round?

Thanks for the thread Im sure I will reference the diagnosis steps you have taken shiuld I fail a test, so far fingers crossed it is always got through.
 
Last edited:
Let me know how you get on, i have scoured the NET for this fault it would seam it doesn't exist, the closest i got was some guy who had the fault and it turned out to be the wheel bearing / end float, so……

I tried to investigate this and after using a puller a slide hammer and oxy acetylene i could not get the drive flange off its absolutely rusted solid on to the drive shaft. could this be the fault ???

Why would it be the fault ? there is no play i the bearing and obviously no excess end float !

Stab in the dark but does the sensor require a good earth ? i think not as its closed loop but maybe i am wrong the whole hub is one big rust lump.
 
Right, FFS here i am revisiting my old post since the last comment i have TOTALLY rebuilt the from axel swivel on the offending side, done bosh new everything from bearings to hub to drive shaft to wheel speed sensor, full of anticipation i plugged the beggar in cleared the last fault code 5-12 and trundled off….

Did the light go out ?? did it F**k, still the same 56 mph light goes out all is fine for a bit then a error 5-12 checked the values this wheel station it still out and thats checking it from the wires at the wheel speed sensor, i have tried 6 sensors in here they all say roughly the same ****, its doing my head in now, i am clearly missing summit ?????

I have checked the values direct from all wheel sensors even changed them about they all read the same except the OSF no matter what sensor i put in it won't generate the AC to spec, i am going loopy i even give the sodding thing a earth in desperation

I am going to ………. feck knows sleep on it
 
Right another ECU

so thats 3 ECU's all saying the same fault 5.12

6 sensors interchanged in that one wheel station all out putting similar results ecu plug end and sensor end

hub TOTALLY rebuilt including new CV

i have to get to 56 MPH to extinguish the ABS light then a while later it will re-appear with code 5.12

What the hell is going on ?????

seriously has someone got a wiring diagram the fault must be spurious from another input
 
replace the sensor wiring from ECU to wheel, that's the only option left... there might be a partial damage in the wiring/plug which becomes "active" at that certain voltage which the sensor outputs at 56mph as the output voltage grows together with the speed...being AC voltage it's not impossible, and the only and last plausible explanation.

download Disc 3 from here http://www.myrangerover.co.uk/MyRangeRover/RAVE.html and you'll get the diagrams
 
Cheers i have continued this on another three with some results too please take a look there and see what you think its driving me loopy, it easy enough to bodge the system off but thats not the way
 
Back
Top